“Our findings suggest that MS patients with allergies have more active disease than those without, and that this effect is driven by food allergies,” said study author Dr. Tanuja Chitnis, an MS specialist, and colleagues.

Multiple sclerosis is a disease of the central nervous system that can affect balance and mobility. Exactly how food allergies might exacerbate MS isn’t clear. But the researchers said the results suggest they might boost MS-related inflammation.

Allergies may also alter gut bacteria, which can produce chemicals that affect the central nervous system, the study authors said.

Because this is an observational study, it can’t prove cause and effect. Further research is needed to confirm the findings, said Chitnis, an associate neurologist at Brigham and Women’s Hospital in Boston, and her co-authors.

The study was published online Dec. 18 in the Journal of Neurology, Neurosurgery and Psychiatry.

It included more than 1,300 MS patients in the United States. The participants provided details about food, drug, or environmental allergies and symptoms between 2011 and 2015. More than 900 had one or more allergies, while the rest had no known allergy.

Of the patients with allergies, almost 600 had an environmental allergy — such as pollen, dust mites, grass or pets. More than 200 had a food allergy, and close to 600 were allergic to certain prescription drugs, the study found.

The researchers assessed the total number of MS relapses each patient had over an average of 16 years. After taking other potentially influential factors into account, they found that food allergies were associated with a 27-times higher rate of MS flare-ups, when compared with patients with no allergies.

They also found that any type of allergy was associated with a greater risk of active disease, as detected by nerve damage on an MRI scan at the last clinic visit. And patients with a food allergy had a more than two-fold increased risk of active disease than those with no allergy.

No link was found between any type of allergy and MS symptom severity or disability, the researchers said in a journal news release.